| 1. |
- Clasén, Kristoffer, 1992, et al.
(författare)
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Investigation of Homogeneous Lean SI Combustion in High Load Operating Conditions
- 2020
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Ingår i: SAE International Journal of Advances & Current Practices in Mobility. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 2641-9645 .- 2641-9637. ; 2:4, s. 2051-2066
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Tidskriftsartikel (refereegranskat)abstract
- Homogeneous lean combustion (HLC) can be utilized to substantially improve spark ignited (SI) internal combustion engine efficiency. Higher efficiency is vital to enable clean, efficient and affordable propulsion for the next generation light duty vehicles. More research is needed to ensure robustness, fuel efficiency/NOx trade-off and utilization of HLC. Utilization can be improved by expanding the HLC operating window to higher engine torque domains which increases impact on real driving. The authors have earlier assessed boosted HLC operation in a downsized two-litre engine, but it was found that HLC operation could not be achieved above 15 bar NMEP due to instability and knocking combustion. The observation led to the conclusion that there exists a lean load limit. Therefore, further experiments have been conducted in a single cylinder research DISI engine to increase understanding of high load lean operation. HLC is known to suppress end-gas autoignition (knock) by decreasing reactivity and temperatures, but during the experiments knock was observed to be prominent and increasing in severity when engine load was increased despite operating ultra-lean close to lambda 2. Knock is normally mitigated by spark retardation which decreases peak cylinder pressure. However, to maintain stable combustion at lambda = 2 the combustion phasing had to be kept close to TC which resulted in high peak cylinder pressures. Therefore, the combustion event had to be balanced in a window where early combustion promoted knock and late resulted in instability and partial burns. A tumble flap was introduced to increase in-cylinder tumble which reduced knock and improved combustion stability. It could be observed that for most load-points assessed; increased tumble could suppress knock and increase the air-dilution limit which proved beneficial in decreasing the NOx emissions. The highest engine load that could be achieved with highly diluted combustion was 16 bar NMEP.
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| 2. |
- Karuppasamy, Arun Prasath, et al.
(författare)
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On the Effects of Turbocharger on Particle Number and Size Distribution in a Heavy - Duty Diesel Engine
- 2021
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Ingår i: SAE International Journal of Advances and Current Practices in Mobility. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 2641-9637 .- 2641-9645. ; 3:2, s. 882-893
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Tidskriftsartikel (refereegranskat)abstract
- Particles emitted from internal combustion engines have adverse health effects and the severity varies based on the particle size. A diesel particulate filter (DPF) in the after-treatment systems is employed to control the particle emissions from combustion engines. The design of a DPF depends on the nature of particle size distribution at the upstream and is important to evaluate. In heavy-duty diesel engines, the turbocharger turbine is an important component affecting the flow and particles. The turbine wheel and housing influence particle number and size. This could potentially be used to reduce particle number or change the distribution to become more favourable for filtration. This work evaluates the effect of a heavy-duty diesel engine's turbine on particle number and size distribution. The particle number (PN) emissions is measured with regard to varying turbine inlet conditions namely: turbine inlet temperature, exhaust mass flow rate and particle concentration at the turbine inlet (by varying fuel injection pressures). It was found that at turbine inlet temperatures of 200°C, PN remains almost constant as the particles were assumed to be held together by the volatile material. However, at 300°C there was an increase in PN across the turbine, and the increase was higher at higher mass flow rates across the turbine. Furthermore, lower injection pressures exhibited a higher rise in PN across the turbine. Interestingly, at 400°C, a reduction in PN across the turbine was observed due to oxidation. This reduction in PN was lesser while there was an increase in mass flow rate. Additionally, with higher injection pressures, a higher reduction in PN was noticed. This result is promising as catalyst coated turbine wheels could potentially enhance the effect thereby reducing PN before the after-treatment system.
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| 3. |
- Ochoterena, Raul, et al.
(författare)
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Apparent Soot Size and Concentration in Combusting Diesel Jets at High Gas Pressures and Temperatures Measured by Combining Quasi-Simultaneous LII, Elastic Light Scattering and Light Extinction
- 2020
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Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2:3, s. 1578-1591
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Tidskriftsartikel (refereegranskat)abstract
- A method for measuring apparent soot particle size and concentration in turbulent combusting diesel jets with elevated and inhomogeneous optical density is presented and discussed. The method is based on the combination of quasi-simultaneous Laser Induced Incandescence (LII), Elastic Scattering (ELS) and Light Extinction (LE) measurements exhibiting a high potential for spatially resolved measurements of carbonaceous particles in flames and residual gases at a given instant. The method evaluates the LII signal by calculating the laser fluence across the flame and compensating for signal trapping, allowing measurements where laser extinction between the flame borders reaches values up to 90 %. The method was implemented by measuring particle size and concentration in the middle sagittal axis of optically dense, combusting diesel jets at a certain time after the start of combustion. Experiments were carried out in the Chalmers High Pressure, High Temperature spray rig under conditions similar to those prevailing in direct injected compression ignition engines. Measurements of apparent particle size and concentration together with volume fraction conferring an instantaneous single-shot case and an average measurement from several consecutive jets are presented and discussed.
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| 4. |
- Jorques Moreno, Carlos, et al.
(författare)
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In-Cycle Closed-Loop Combustion Control for Pilot Misfire Compensation
- 2020. - 2020
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Ingår i: SAE Powertrains, Fuels & Lubricants Meeting. - : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Pilot injections are normally used for the reduction of diesel engine emissions and combustion noise. Nonetheless, with a penalty on the indicated thermal efficiency. The cost is reduced by the minimization of the pilot mass, which on its counterpart increases the risk of pilot misfire. Pilot misfire can have a higher penalty on the indicated efficiency if it is not compensated adequately. This paper investigates how in-cycle closed-loop combustion control techniques can reduce the effects of pilot misfire events. By closed-loop combustion control, pilot misfire can be detected and counteracted in-cycle. Two injection strategies are investigated. The first is the control of the main injection, the second includes an additional second pilot injection. Based on the in-cycle misfire diagnose, two architectures are investigated. The first uses a cycle-To-cycle controller to set the main injection under each scenario. The second is a fully in-cycle controller with feedback from predictive models. All the algorithms were tested experimentally in a Scania D13 engine. The results confirmed that in-cycle closed-loop combustion control can effectively reduce the effects of pilot misfire. An error of +1.5CAD on the main SOC and-0.5bar IMEP on the engine load was reduced to 0±0.6CAD and 0±0.4bar IMEP using the cycle-To-cycle architecture. The predictive in-cycle control can further reduce the error of the main SOC to 0±0.4CAD and 0±0.2bar IMEP for the engine load. These two approaches had one degree of freedom, and therefore only one of the combustion timing parameters (SOC or CA50) was regulated successfully. With the additional degree of freedom of the second pilot injection, the misfire effects were not only reduced, but also fully counteracted. The methods are limited by the time window where pilot misfire observability and controllability overlap. This is set by the injections' separations and the respective ignition delays. The second pilot injection can be further improved by the regulation of its injection timing and duration. The results can enhance the nominal set-up optimization by including the in-cycle controllability and regulation performance in the constraints.
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| 5. |
- Jorques Moreno, scania, et al.
(författare)
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Cylinder Pressure Based Method for In-Cycle Pilot Misre Detection
- 2020
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Ingår i: International Journal of Advances and Current Practices in Mobility. - : SAE International. - 2641-9645. ; 2:2, s. 488-502
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Tidskriftsartikel (refereegranskat)abstract
- For the reduction of emissions and combustion noise in an internal combustion diesel engine, multiple injections are normally used. A pilot injection reduces the ignition delay of the main injection and hence the combustion noise. However, normal variations of the operating conditions, component tolerances, and aging may result in the lack of combustion i.e. pilot misfire. The result is a lower indicated thermal efficiency, higher emissions, and louder combustion noise. Closed-loop combustion control techniques aim to monitor in real-time these variations and act accordingly to counteract their effect. To ensure the in-cycle controllability of the main injection, the misfire diagnosis must be performed before the start of the main injection. This paper focuses on the development and evaluation of in-cycle algorithms for the pilot misfire detection.Based on in-cylinder pressure measurements, different approaches to the design of the detectors are compared. For non-adaptive methods, a constant threshold, direct misfire probability, and posterior misfire probability detectors are investigated. For adaptive methods, an adaptive threshold update is suggested, an adaptation of the predictive stochastic models and a sensor fusion of them is proposed to increase the detection performance.A Scania D13 engine is used to perform the experiments under different operating conditions. The effectiveness of the algorithms is tested for different engine speeds, rail pressures, injection durations, starts of injection, EGR levels, and fuels. The results show that the observability of in-cycle pilot misfire depends on the operating conditions, and its detection can be performed successfully before the start of the main injection. With a maximum in-cycle pilot misfire observability of 98.5%, a maximum successful detection ratio of about 96% can be reached with the proposed in-cycle pilot misfire detectors. The algorithms are therefore suitable for in-cycle closed-loop combustion control feedback. By including cycle-to-cycle adaptation, the detection performance and robustness are improved significantly. The limitations are directly related to the signal-to-noise ratio of each operating condition.
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| 6. |
- Larsson, Tara, 1993-, et al.
(författare)
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A Batch Blending System for Continuous Production of Multi-Component Fuel Blends for Engine Laboratory Tests
- 2020
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Ingår i: SAE International Journal of Advances and Current Practices in Mobility. - SAE : SAE International. - 2641-9645.
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Konferensbidrag (refereegranskat)abstract
- The increased rates of research on complex fuel blends in engine applications poses a need for more efficient and accurate fuel blending processes in engine laboratories. Making the fuel blending process automatic, effective, accurate and flexible saves time, storage space and cost without compromising the tests of future fuel alternatives. To meet these requirements, an automatic fuel blending system, following a sequential batch process, was designed and tested for engine laboratory application.The fuel blending system was evaluated in terms of functionality, safety, accuracy and repeatability. The functionality and safety was evaluated through a risk analysis. Whereas, the accuracy and repeatability of the system was investigated through blend preparation tests. The results show that the minimum fuel mass limitation of the system is 0.5 kg. This allows for blends with fuel ratios as low as 7 vol-% to be prepared by the system. The mean relative errors for all tested fuels are below 5% by mass, enabling a wide range of fuels to be used in the system. The absolute error in fuel ratio is 0.5 vol-% or less. In addition, the relative error in fuel ratio of the prepared blends is below 4% for all but one of the tested blends. Moreover, the system can prepare all of the tested fuel blends in 5 minutes.
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| 7. |
- Piracha, Muddassar, 1987, et al.
(författare)
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Feedback Control of Synchronizers for Reducing Impacts During Sleeve to Gear Engagement
- 2020
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Ingår i: SAE Technical Papers. - : SAE International. - 0148-7191 .- 2688-3627. ; 2:4, s. 2067-2080
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a feedback control strategy aimed to reduce noise and wear during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on a new dog teeth position sensor developed by China Euro Vehicle Technology AB and existing speed sensors in the transmission. During gear shifting, noise is generated by impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization. Besides noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth, hence reducing the lifespan of the transmission. The presented control strategy controls speed synchronization such that the impact between sleeve and idler gear dog teeth, before the start of torque ramp up, is avoided. Since drag torque is an important factor in speed synchronization, this paper also contains an algorithm to identify friction torque coefficient in the transmission. The identification method ensures that the controller adapts to varying conditions without the need for offline calibration. The control strategy is developed for standard automatic gear shifting operations but minor adaptations in the algorithm also make it capable of handling gear shifts requested by the driver. The output signal of the control strategy is acceleration request on idler gear during speed synchronization. To make controller easier to implement and minimize shift time, the acceleration request only has two values, either maximum value or zero. The control strategy is designed in such a way that it can easily be integrated in the existing transmission control software. By applying the control strategy on a detailed simulation model, it is shown that the impacts during gear engagement are significantly reduced.
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| 8. |
- Singh, Vikram, et al.
(författare)
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Optimization and Evaluation of a Low Temperature Waste Heat Recovery System for a Heavy Duty Engine over a Transient Cycle
- 2020
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Ingår i: SAE Technical Papers. - : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- Powertrain efficiency is a critical factor in lowering fuel consumption and reducing the emission of greenhouse gases for an internal combustion engine. One method to increase the powertrain efficiency is to recover some of the wasted heat from the engine using a waste heat recovery system e.g. an organic Rankine cycle. Most waste heat recovery systems in use today for combustion engines use the waste heat from the exhaust gases due to the high temperatures and hence, high energy quality. However, the coolant represents a major source of waste heat in the engine that is mostly overlooked due to its lower temperature. This paper studies the potential of using elevated coolant temperatures in internal combustion engines to improve the viability of low temperature waste heat recovery. The paper first uses engine experiments and multi-linear regression analysis to model the indicated efficiency and recoverable power for a Scania D13 heavy duty engine across a range of engine loads, speeds and coolant temperatures. The recoverable power is obtained from simulations of a dual loop waste heat recovery system using ten working fluids as potential candidates for recovering heat from the exhaust gases and the coolant. The paper then investigates the maximum potential fuel consumption benefit by using elevated coolant temperatures for the Scania engine running on the World Harmonized Transient Cycle. From the simulation results, it was seen that cyclopentane and methanol were the best performing working fluids for the coolant and exhaust gas heat sources respectively. From the analysis on the World Harmonized Transient cycle, when using the best performing working fluids and elevated coolant temperatures, a potential net reduction in fuel consumption of 9% could be obtained.
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| 9. |
- Waqas, Muhammad Umer, et al.
(författare)
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Effect of Intake Temperature and Engine Speed on the Auto-Ignition Reactivity of the Fuels for HCCI Fuel Rating
- 2021
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Ingår i: SAE Technical Papers. - : SAE International. - 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- The current research octane number (RON) and motor octane number (MON) gasoline tests are inadequate for describing the auto-ignition reactivity of fuels in homogeneous charge compression ignition (HCCI) combustion. Intake temperature and engine speed are two important parameters when trying to understand the fuel auto-ignition reactivity in HCCI combustion. The objective of this study was to understand the effect of high intake temperature (between 100 and 200 °C) and engine speed (600 and 900 rpm) on the auto-ignition HCCI reactivity ratings of fuels using an instrumented Cooperative Fuel Research (CFR) engine. The fuels used for this study included blends of iso-octane/n-heptane, toluene/n-heptane, ethanol/n-heptane, and gasolines with varying chemical compositions and octane levels. The CFR engine was operated at 600 and 900 rpm with an intake pressure of 1.0 bar and an excess air ratio (lambda) of 3. It was found that the relative HCCI reactivity ranking of the gasolines with a RON of 98 was constant at both engine speeds and high intake temperatures (150 °C and 200 °C). This implied that for HCCI fuel ratings, there exists a threshold intake temperature beyond which further increases in temperature do not change the relative rankings of the fuel's HCCI reactivity. At these high intake air temperatures, changes in engine speed between 600 and 900 rpm did not affect the HCCI ratings of the RON98 gasolines either. However, the effects of intake temperature (between 150 and 200 °C) and engine speed (600 and 900 rpm) did become apparent when additional gasoline octane levels and chemical compositions were investigated.
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